Metal forming

ABSTRACT

THE THIN PART. THE COVER SHEETS ARE MECHANICALLY RESTRAINED FROM SLIPPAGE BY EDGE WELDING. A METHOD OF METAL FORMING, AS BY ROLLING, A THIN SHEET METAL PART SUCH AS TITANIUM IN PACK FASHION WHEREBY THE PART TO BE FORMED IS SANDWICHED BETWEEN INNER AND OUTER COVER SHEETS OF SUFFICIENT STRENGTH TO PROVIDE SUPPORT FOR     D R A W I N G

March 2, 1911 G. P. ETAL 3,566,661

METAL FORMING Fild July 29', 1968 K1 1. (Prior ark) I ---%Bi l XINVENTORS. Gerald M Caflerfy. Fredenck Rudolphlr. BY Harry [2 Sch onwmu, R. VLJLI;

AGENT v United States Patent Office Patented Mar. 2, 1971 3,566,661METAL FORMING Gerald P. McCalferty, Churchville, Pa., Frederick Rudolph,Jr., Cherry Hill, N.J., and Harry P. Schane,

Lafayette Hill, Pa., assignors to The Budd Company,

Philadelphia, Pa.

Filed July 29, 1968, Ser. No. 748,444 Int. Cl. B21b 1/00; B21c 37/02;B23p 17/00 US. Cl. 72--365 3 Claims ABSTRACT OF THE DISCLOSURE A methodof metal forming, as by rolling, a thin sheet metal part such astitanium in pack fashion whereby the part to be formed is sandwichedbetween inner and outer cover sheets of sufficient strength to providesupport for the thin part. The cover sheets are mechanically restrainedfrom slippage by edge welding.

The forming of sheet metal parts which have non planar shapes and whichare composed of a low elongation material such as titanium has generallybeen formed by a step expansion process. An expansion process whethermechanical or hydraulic is limited to a safe percentage of elongation ofthe material before stress relieving and reexpanding. As a result, if apart contains radical bend radii or shapes requiring large percentages(IO-20%) of stretch, multiple and costly operations must be performed tocomplete the part formation.

It is an object of this invention, therefore, to provide an improvedmethod of metal forming which avoids one or more of the disadvantages ofthe prior-art methods and which has improved efficiency.

It is still another object of this invention to provide an improvedmethod as by a rolling process of forming an object of non-planar shapedcross sectional contour, which circumvents the multiple and costlyoperations previously used in forming such parts.

For a better understanding of the present invention together with otherand further objects thereof, reference is had to the followingdescription taken in connection with the accompanying drawing and itsscope will be pointed out in the appended claims.

In the drawings FIG. 1 is a view of one form of a prior-art arrangementshowing an elevational view of a support form and a cooperable rollerelement for rolling a bead in a thin walled titanium blank;

FIG. 2 is an elevational view of a support form and roller apparatus andembodying the method of the present invention;

FIG. 3 is an elevational view of the metal forming apparatus of FIG. 2showing the metal blank pack being subjected to radical bend radii;

FIG. 4 is a view similar to FIG. 2 and illustrating a modified form ofthe invention.

This invention is useful in avoiding multiple stretching andintermediate stress relieving operations. With certain types of titaniumthe total amount of stretch forming may be extended as high as 11%.Expansion, however, being generally limited to 2 to3 percent perstretching operation as for example with 6AL, 4V titanium alloy, leadsto multiple operations with stress relieving steps therebetween.

As a proposed solution to this problem it has been suggested to performpreliminary forming operations before endeavoring to obtain the finalsize of an object on an expansion machine. Such forming operation may beaccomplished by rolling or beading the end bend radii inward therebyremoving the major amount of percentage expansion required and allowinga single sizing operation in the order of 2 percent stretch.

Referring to FIG. 1 a thin sheet of material 10, such as titanium isshown contacting a cylindrical support 11. The support form includes anencircling groove 12 adjacent one end thereof and terminates in astepped shoulder 13 which enables the support form 11 to be gripped forrotation as for example in a lath chuck, not shown. A roller 15 mountedfor rotation about axis 17 may be moved toward and away from thetitanium work piece 10 in in-line relationship with groove 12 asindicated by arrow A. The latter groove 12 includes outer radialsurfaces 18. It has been found that upon advancing the feed of theroller 15 inwardly to engage the titanium blank while rotating thesupport form 11 about its axis, the results were unsatisfactory. Thethin titanium sheet buckled and wrinkled badly over both radii portionsas at 18 of the groove 12. It is believed that the buckling was due tolack of support over the area indicated as at 20 between the radiimarginal edges 18 of groove 12 and the outermost peripheral tangent edge21 of roller 15.

Referring now to FIG. 2 and in accordance with the present invention, athin titanium blank 10 is shown engaged by an inner cover sheet 25 andan outer cover sheet 27. The cover sheets 25 and 27 are larger in areathan the blank 10 and extend beyond the right hand edge 10a of the blankas seen in FIG. 2. In order to prevent relative slippage of the innercover sheet 25 relative to the outer cover sheet 27, the marginal edgesof the sheets may be welded as at 30, 31. When so secured together thetitanium sheet 10, and cover sheets 25, 27 constitute a sandwich pack32. Thereafter die set means 33 including a support form 34 and rollermeans 35 is provided. The support form 34 includes a groove 36 extendinginwardly from its external surface 37. The support form may include achuck land 37 of smaller diameter than that defined by external surface37 to enable the support form to be rotated about its longitudinal axisby lathe means not shown. The roller means 35 are of smaller width thangroove 36 and are in addition suitably mounted for rotation about axisXX parallel to that of the axis of support 34. The roller means 35 areadapted to be moved normal to the axis XX as indicated by the arrow B.The sandwich pack 32 is placed upon the support form so that the innercover sheet 25 coacts with the external surface 37 of the support formto span groove 36 and thereafter the roller means 35 are bodily movedtoward the groove 36 to coact with the external cover sheet 27. Uponexerting sulficient mechanical pressure inwardly while rotating thesupport form 34, the outer cover sheet 27, the blank 10 and the innercover sheet are deformed and caused to enter the groove 36 as seen inFIG. 3. Thereafter the roller may be removed out of engagement with thesandwich pack. The inner and outer cover sheets may then be out alongthe lines Y-Y to remove the edge weld fastening 30. The top cover sheet27 is then suitably removed from engagement with the blank 10 and thelatter in turn removed from contact with the inner cover sheet 27.

With reference now to FIG. 4 there is shown a modified form of theinvention. The roller means 35 and the support form means 34 providedmay be identical to those shown in FIGS. 2 and 3. A sandwich pack 42 isprovided and consists of an inner cover sheet 43, outer cover sheet 45and a thin blank of titanium 10 sandwiched therebetween. The inner coversheet 43 is of greater thickness than the outer cover sheet 45 and bothcover sheets 43, 45 are edge welded as at 46 to prevent slippagerelative each other 10. The latter blank 10 is of smaller area than thecover sheets and includes an edge 10a offset from the edge weld 46. Aspreviously stated relative to FIGS. 2 and 3 the roller means 35 may bemoved inwardly to compress the material of the sandwich pack into thegroove 36. Upon withdrawing the roller means the edge weld of the packmay be suitably removed as by cutting along line Y-Y and the inner andouter cover sheets removed from the thin titanium blank 10. It has beenfound that increases as to the width of the groove 36 or the radii 47 ofthe groove, may be more easily accommodated as a result of increasingthe support for the blank by the provision of increasing the thicknessof the bottom cover sheet 43.

While there have been described what are at present considered to be thepreferred embodiments of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from this invention, and it is, therefore,aimed in the appended claims to cover all such changes and modificationsas fall within the true spirit and scope of the invention.

What is claimed is:

1. A method of forming a metal sheet blank into an object of non-planarshaped cross sectional contour, comprising providing inner and outermetal sheets of an area exceeding that of said blank, said inner andouter metal member comprising a rigid support form having a surfaceportion defining a groove and said second die set member comprising aroller, disposing said sandwich pack in a position between said die setmembers with said inner sheet in a position to first enter said groove,and thereafter providing relative movement between said roller and saidsupport to cause a portion of said sandwich pack to enter said groove todeform said blank whereby said blank is enable to slip relative to saidinner and outer cover sheets to preclude thinning out of said blankduring said deformation.

2. In the method as set forth in claim 1 wherein said inner metal sheetis of greater strength than said outer metal sheet.

3. In the method as set forth in claim 2 wherein said inner metal sheetis of greater thickness than said outer sheet.

References Cited UNITED STATES PATENTS 2,837,817 6/1958 Kelley 29--4243,063,142 11/ 1962 Kroon 29-424 3,263,319 8/1966 Tifft et a1 29-4233,460,367 8/ 1969 Subovici 72-365 1,648,046 11/ 1927 Fulton 138-1213,143,794 8/1964 Martin-Hurst 29-454 CHARLES W. LANHAM, Primary ExaminerR. M. ROGERS, Assistant Examiner U.S. Cl. X.R. 29-423; 72-379

